Computer Networking: A Top-Down Approach Flashcards
What is twisted pair copper wire? What is its peak transmission speed?
The least expensive and most commonly used guided transmission medium. 10Gbps.
What is a coaxial cable? What is its peak transmission speed?
A coaxial cable is cable consisting of two copper wires, running concentric, with special insulation and shielding. Tens of Mbps.
What is a fiber optic cable? What is its peak transmission speed?
A fiber optical cable is a thin, flexible medium that conducts pulses of light, with each pulse translating to a bit. Hundreds of Gbps
What is a packet?
A packet is a basic unit of data that’s grouped together and transferred over a computer network from a source end system to a destination end system.
What is Store-and-Forward transmissioning?
Store-and-Forward is a method of transmission in which the packet switch must receive the entirety of a packet before transmitting the first bit of the packet onto the outbound link.
What is an output buffer or output queue?
An output buffer is a temporary storage area that stores packets that the router is about to send into a link.
Example: The router uses the output buffer to hold packets temporarily before transmitting them over the network.
What is packet loss and how does it occur?
Packet loss is when either the arriving packet or one of the already-queued packets is dropped. This occurs because a switch’s output buffer is finite, and when attempting to add packets to an already full output buffer, it will become overcrowded and drop a packet.
Example sentence: Packet loss can occur during network congestion.
What is a forwarding table and what is its usage in routing?
A forwarding table is the component of a router that maps destination addresses to its outbound links. When a packet arrives at a router, the router examines the address and searches its forwarding table using the address to find the appropriate outbound link. The packet is then directed to the proper outbound link.
Additional information: The forwarding table is crucial for efficient routing.
What is a point of presence (PoP)?
A PoP is a group of one or more routers (at the same location) in the provider’s network where customer ISPs can connect into the provider ISP.
Example sentence: The PoP in New York City serves as a hub for connecting customer ISPs.
What is network peering?
When two nearby ISPs directly connect their networks together so that all the traffic between them passes over the direct connection rather than through upstream intermediaries.
Example sentence: Network peering helps reduce latency.
What is an internet exchange point (IXP)?
A meeting point where multiple ISPs can peer together, typically in a stand-alone building with its own switches.
Example sentence: The IXP in Amsterdam is one of the largest in Europe.
What is transmission delay?
Transmission delay is the amount of time required to push all of a packet’s bits into the proper link. Often measured in milliseconds.
Example sentence: High transmission delay can impact real-time communication.
What is propagation delay?
Propagation delay is the amount of time required to propagate from the beginning of the link to router B. The speed of this is determined by the distance between the two routers.
Example sentence: Propagation delay is influenced by the medium through which the signal travels.
What are the 5 layers of Internet Protocol?
The Internet protocol stack consists of five layers: physical, link, network, transport, and application.
Additional information: Each layer has specific functions in the communication process.
What is the application layer, and what are some of the most common application layer internet protocols?
The application layer is the layer where network applications and their application-layer protocols reside. Examples of application-layer protocols include: HTTP, DNS, SMTP, FTP.
Example sentence: The application layer is responsible for user interactions on the network.
What is the transport layer and what is its purpose?
The internet’s transport layer transports application-layer packets of information between application endpoints. It manages TCP and UDP, offering either a guaranteed delivery broken down into smaller, digestible packets or a less controlled service of transportation respectively.
Example sentence: The transport layer ensures reliable data delivery.
What is the network layer, and what is its purpose?
The network layer is responsible for moving network-layer packets from one host to another. It provides the internet protocol (IP ) and multiple routing protocols to networks.
Example sentence: The network layer determines the best path for data transmission.
What is the link layer, and what are examples of link-layer protocols?
The link layer moves packets from one node to the next node in the route. Examples include Ethernet, Wi-Fi, and the CAN’s DOCSIS protocol.
Example sentence: The link layer ensures reliable communication between adjacent nodes.
What is the physical layer and what are some examples?
The physical layer is responsible for moving the individual bits within a link-layer packet from one node to the next. Examples of Ethernet’s physical layer protocols are: twisted-pair copper wire, single-mode fiber optics, coaxial cable, etc.
Example sentence: The physical layer deals with the actual transmission of data signals.
What is a socket?
A socket is the interface between the application layer and the transport layer within a host.
Example: The socket allows communication between different applications on the same host.
What is a port number used for?
A port number is used for identifying the receiving socket when sending transporting information.
Example: Port number 80 is commonly used for HTTP traffic.
What are transport services available to applications?
Some transport services that are available to applications include reliable data transfer, throughput management, timing, and security.
No additional information.
Why is HTTP considered a stateless protocol?
HTTP is considered a stateless protocol because it maintains no information about the clients it serves.
Example sentence: When a client makes a request to a server, the server does not retain any information about the client once the request is complete.
What is the round-trip time of a packet?
The round-trip time of a packet is the time it takes for a small packet to travel from client to server then back to the client.
Additional information: Round-trip time is a critical metric for measuring network performance.
